The background description provided herein is for the purpose of generally presenting the context of the disclosure. Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Photonic integrated circuits may be considered a promising candidate for next generation interconnects for data center and high performance computing. Optical waveguide-based photonics integrated circuits such as lasers, modulators, and detectors may be typically fabricated on silicon-on-insulator (SOI) wafers. At a high data rate, e.g., larger than 10 Gb/s, a minor laser instability may cause burst bit errors and may disrupt the operations on a link of the interconnects significantly. Laser instability may be caused by feedback or reflections to the laser.
An optical isolator may be used for protecting photonics integrated circuits from reflections because an optical isolator may allow light waves to propagate in specified directions while preventing the propagation of light waves in undesired directions. However, a traditional optical isolator may be a standalone device, which may be bulky, expensive, and complicated to integrate. In addition, many existing on-chip optical isolators may have high insertion loss and complicated manufacturing processes. High insertion loss may be a challenging barrier to the commercialization of on-chip optical isolators, while complicated manufacturing processes for on-chip optical isolators may be costly and hard to manage.